CN117352587A - Diamond nuclear detector of hydrogen passivation silicon terminal ohmic contact electrode and preparation method thereof - Google Patents

Abstract

The invention discloses a diamond nuclear detector of a hydrogen passivation silicon terminal ohmic contact electrode and a preparation method thereof, wherein the method comprises the following steps: selecting diamond according to the preset impurity content requirement and the preset dislocation density requirement, and cleaning to obtain a diamond substrate; forming a first silicon film on the upper surface of the diamond substrate; performing high-temperature hydrogen plasma treatment on the diamond containing the silicon film in MPCVD to form a first silicon terminal doped diamond layer and a first hydrogen passivated silicon terminal diamond layer; forming a second silicon film on the lower surface of the diamond substrate; the lower surface adopts the same process to form a second silicon terminal doped diamond layer and a second hydrogen passivated silicon terminal diamond layer; and preparing a first electrode on the surface of the first hydrogen-passivated silicon terminal diamond layer, and preparing a second electrode on the surface of the second hydrogen-passivated silicon terminal diamond layer to obtain the diamond nuclear detector. The preparation method of the diamond nuclear detector of the hydrogen passivation silicon terminal ohmic contact electrode can improve the device performance by improving the contact characteristic.

Description

Diamond core detector with hydrogen-passivated silicon terminal ohmic contact electrode and preparation method

Technical field

The invention belongs to the field of semiconductor nuclear detectors, and specifically relates to a diamond nuclear detector with a hydrogen-passivated silicon terminal ohmic contact electrode and a preparation method.

Background technique

Diamond is an ultra-wide bandgap semiconductor material with a large bandgap (5.5eV), strong radiation resistance, high carrier mobility, small relative dielectric constant, high thermal conductivity, and good human body equivalence. (atomic number is close to that of the human body model) and strong ability to survive in extreme environments (chemical inertness, high melting point, high hardness), etc., which are very suitable for the intensity and energy distribution of nuclear radiation in extreme environments such as strong irradiation and fast pulses. , time response and spatial distribution for detection. Compared with traditional semiconductor nuclear detectors such as silicon, it has significant performance advantages and is widely used in fields such as nuclear power generation, space science, industrial detection, radioactive medical treatment, and environmental protection detection.

The working principle of the diamond core detector is that after the incident ray interacts with the diamond detector material, electron-hole pairs are excited inside the detector and driven by the electric field, and are collected at the electrode end to generate an electrical signal to the outside. Its performance is usually measured in terms of charge collection efficiency (CCE), energy resolution, current-voltage (I-V) characteristics and time response characteristics. CCE reflects the proportion of electron-hole pairs generated by rays inside the detector that can be collected at the electrode end. The CCE is usually required to be as close to 100% as possible; the energy resolution reflects the resolution accuracy of the device for ray energy; I-V characteristics and time response can describe the intensity of radiation and its change over time, which usually require excellent linearity, large gain and dynamic range, and extremely fast response time.

The above performance indicators of diamond nuclear detectors are greatly affected by material quality and electrode contact. In terms of material quality, due to the large band gap of diamond material, the commonly used N-type dopants (nitrogen and phosphorus) and P-type dopants (boron) have low solid solubility and large activation energy, making it difficult to form silicon detectors at room temperature. The commonly used PN junction, PIN junction and Schottky detector structures form scattering centers, traps and deep energy level recombination centers in diamond, which seriously affects the radiated carriers (electron-hole pairs). The transport characteristics inside the device cause the charge to be unable to be completely collected, which reduces the performance of the above-mentioned device. Therefore, the use of high-purity intrinsic diamond materials to prepare nuclear detectors can effectively improve device performance. In terms of electrode contact, contact resistance and contact interface trap effects are also key bottlenecks that deteriorate device performance. The large additional impedance caused by excessive contact resistance will cause the device output current and gain to decrease, and the response speed will slow down; while interface traps cause The carrier capture effect will cause difficulty in transporting electron-hole pairs near the interface, causing linearity to deteriorate and reducing CCE and energy resolution characteristics; therefore, high-purity intrinsic diamond is used to prepare it with low contact resistance and low interface The trap effect of high-performance ohmic contact electrodes in diamond nuclear detectors is of great significance. Since the surface work function of high-purity intrinsic diamond is higher than that of currently known commonly used metal materials, it is difficult to form a good ohmic contact and has a high gold half-contact barrier and contact resistance. Moreover, due to the obstruction of the contact barrier, radiation is generated. After the current flows out of the device, the electrode terminal cannot inject the carriers required to restore the neutral state, which will cause an interface polarization electric field, thereby reducing the device performance.

Currently, diamond surface terminal control technology is used internationally to solve the above technical problems, but there are still some problems.

First, the hydrogen-terminated diamond surface is used to form ohmic contact with the metal. The ohmic contact resistivity is generally 10 ^-4 Ω·cm ² and the ohmic contact resistance is about 3.2Ω·mm. However, limited by the single bond characteristics of hydrogen atoms, it is difficult for hydrogen-terminated diamond to form stable chemical bonds with metal materials to achieve good contact and adhesion effects. Moreover, the current contact resistivity between hydrogen-terminated diamond and metal electrodes is also high. .

The second is to use a silicon-terminated diamond surface to form ohmic contact with the metal. Silicon, like hydrogen, has a smaller electronegativity than carbon, and the electronegativity difference between bonding atoms in the C–Si structure is larger than that in the C–H structure, so silicon-terminated diamond can achieve The higher carrier concentration and surface conductivity of hydrogen-terminated diamond are expected to achieve lower resistance ohmic contact with metals.

However, the two current silicon-terminated diamond preparation technologies still have the following shortcomings. One is to deposit an extremely thin Si film on the hydrogen-terminated diamond surface through molecular beam epitaxy (Molecular Beam Deposition, MBD), and then in-situ at high temperatures. After annealing, silicon terminals are prepared by forming C-Si bonds on the surface. However, the silicon film prepared by this method is easily oxidized to form a large number of Si-O bonds, and an insulating silicon dioxide layer is formed on the diamond surface, making it impossible to prepare low-resistance ohmic contact electrodes on diamond core detectors. The other method is to first deposit a silicon film on the surface of the diamond, and then place it in a sealed quartz tube and heat it to form a silicon terminal on the diamond surface. However, this technology will also cause oxidation on the silicon terminal on the diamond surface, making it difficult to prepare low-resistance ohms. Contact electrode. In addition, in the above-mentioned traditional method, Si is at the most surface, and the oxygen atoms are Si-O bonds formed by oxidation in the air atmosphere. The formed silicon dioxide layer itself has a high defect density, and the silicon oxidation is incomplete, and the Si dangling bonds High density will cause serious interface trap effects, which are difficult to meet the development requirements of high-performance diamond nuclear detectors.

Contents of the invention

In order to solve the above-mentioned problems existing in the prior art, the present invention provides a diamond core detector with a hydrogen-passivated silicon terminal ohmic contact electrode and a preparation method. The technical problems to be solved by the present invention are achieved through the following technical solutions:

A method for preparing a diamond core detector with a hydrogen-passivated silicon terminal ohmic contact electrode, including:

Select high-purity intrinsic diamond according to the preset impurity content requirements and preset dislocation density requirements, and clean them to obtain a diamond substrate;

Form a first silicon film on the upper surface of the diamond substrate;

Performing a preset process on the first silicon film includes: using hydrogen plasma to provide a high-temperature environment in MPCVD, causing silicon atoms in contact with the upper surface of the diamond substrate to thermally diffuse into the diamond lattice, forming a The first silicon terminal of the C-Si bond is doped with a diamond layer; then the hydrogen plasma pressure and power are increased to etch and remove the residual silicon film that has not diffused into diamond on the surface, and finally the first silicon terminal is doped with a diamond layer. A first hydrogen-passivated silicon-terminated diamond layer with C-Si-H bonds is formed on the surface;

Form a second silicon film on the lower surface of the diamond substrate after completing the preset process;

Perform the preset process on the second silicon film to form a second silicon terminal doped diamond layer and a second hydrogen passivated silicon terminal diamond layer;

A first electrode is prepared on the surface of the first hydrogen-passivated silicon-terminated diamond layer, and a second electrode is prepared on the surface of the second hydrogen-passivated silicon-terminated diamond layer, thereby obtaining a diamond core detector.

In one embodiment of the present invention, the preset impurity content requirement is that the impurity concentration of nitrogen and boron is less than 5 ppb; the preset dislocation density requirement is that the dislocation density is less than 10 ³ cm ^-2 .

In one embodiment of the present invention, cleaning the selected high-purity intrinsic diamond includes:

The selected high-purity intrinsic diamond was ultrasonically cleaned sequentially for 15 minutes in a strong acid mixed solution of H ₂ SO ₄ :HNO ₃ , acetone, ethanol, and deionized water at 200°C.

In one embodiment of the present invention, forming a first silicon film on the upper surface of the diamond substrate includes:

On the upper surface of the diamond substrate, an intrinsic silicon target material with a purity of 99.9999% is used to deposit a silicon film with a thickness of 250 nm to 350 nm through magnetron sputtering as the first silicon film.

In one embodiment of the present invention, performing a preset process on the first silicon film includes: using hydrogen plasma to provide a high-temperature environment in MPCVD to thermally diffuse silicon atoms in contact with the upper surface of the diamond substrate. Enter the diamond lattice to form a first silicon terminal doped diamond layer with C-Si bonds; then increase the hydrogen plasma pressure and power to etch and remove the residual silicon film that has not diffused into the diamond on the surface, and finally in the A first hydrogen-passivated silicon-terminated diamond layer with C-Si-H bonds is formed on the upper surface of the first silicon-terminated doped diamond layer, including:

Place the diamond substrate with the first silicon film deposited on the surface into MPCVD, and under the conditions of 500-600 sccm hydrogen flow, 50-100 mbar pressure, and 2000-2500 W microwave power, heat it up to 600-800°C to perform hydrogen plasma etching. High-temperature treatment for 5 to 10 minutes allows silicon atoms to thermally diffuse into the diamond lattice to generate C-Si bonds, forming the first silicon terminal doped diamond layer;

Under the conditions of 600-700sccm hydrogen flow, 150-200mbar pressure, and 3500-4000W microwave power, raise the temperature to 800-1000°C and perform hydrogen plasma etching for 5-10 minutes; use hydrogen plasma to etch the remaining first silicon film. After the first silicon film is completely removed, the action of hydrogen plasma under high temperature and high pressure is used to generate C-Si-H bonds on the upper surface of the first silicon terminal doped diamond layer to form the first hydrogen passivation. Silicon terminated diamond layer.

In one embodiment of the present invention, a first electrode is prepared on the surface of the first hydrogen-passivated silicon-terminated diamond layer, and a second electrode is prepared on the surface of the second hydrogen-passivated silicon-terminated diamond layer, including:

When the material of the electrode is Au, an Au metal layer of 80 to 120 nm is deposited using an electron beam evaporation process in a preset area on the surface of the first hydrogen-passivated silicon terminal diamond layer to form a metal electrode as the first electrode;

In a preset area on the surface of the second hydrogen-passivated silicon terminal diamond layer, an 80-120 nm Au metal layer is deposited using an electron beam evaporation process to form a metal electrode as the second electrode.

In one embodiment of the present invention, a first electrode is prepared on the surface of the first hydrogen-passivated silicon-terminated diamond layer, and a second electrode is prepared on the surface of the second hydrogen-passivated silicon-terminated diamond layer, including:

When the materials of the electrode are Ti and Au, a Ti metal layer of 20 to 30 nm and a Ti metal layer of 90 to 90 nm are sequentially deposited using an electron beam evaporation process in a preset area on the surface of the first hydrogen-passivated silicon terminal diamond layer. The 100nm Au metal layer is annealed in a rapid thermal annealing RTP equipment to form an ohmic contact electrode as the first electrode;

In a preset area on the surface of the second hydrogen-passivated silicon terminal diamond layer, a 20-30nm Ti metal layer and a 90-100nm Au metal layer are sequentially deposited using an electron beam evaporation process, and the rapid thermal annealing RTP equipment Medium annealing treatment to form an ohmic contact electrode as the second electrode;

Wherein, the time of the annealing treatment is 25-30 seconds, and the temperature of the annealing treatment is 600-650°C.

In one embodiment of the present invention, a first electrode is prepared on the surface of the first hydrogen-passivated silicon-terminated diamond layer, and a second electrode is prepared on the surface of the second hydrogen-passivated silicon-terminated diamond layer, including:

When the materials of the electrode are Ti, Pt and Au, a 40-60 nm Ti metal layer, The 80-100nm Pt metal layer and the 40-60nm Au metal layer are rapidly thermally annealed in a nitrogen atmosphere to form an ohmic contact electrode as the first electrode;

In a preset area on the surface of the second hydrogen-passivated silicon terminal diamond layer, an electron beam evaporation process is used to sequentially deposit a 40-60 nm Ti metal layer, an 80-100 nm Pt metal layer, and a 40-60 nm Au metal layer. layer, perform rapid thermal annealing in a nitrogen atmosphere to form an ohmic contact electrode as the second electrode;

Wherein, the temperature of the rapid thermal annealing is 750-850°C, and the time of the rapid thermal annealing is 20-30 seconds.

A diamond core detector with hydrogen passivated silicon terminal ohmic contact electrode, including:

a diamond substrate, a first silicon terminal doped diamond layer, a first hydrogen passivated silicon terminal diamond layer, a second silicon terminal doped diamond layer, a second hydrogen passivated silicon terminal diamond layer, a first electrode and a second electrode; in,

The first silicon terminal doped diamond layer, the first hydrogen passivated silicon terminal diamond layer and the first electrode are arranged on the upper surface of the diamond substrate in order from bottom to top;

The second silicon terminal doped diamond layer, the second hydrogen passivated silicon terminal diamond layer and the second electrode are arranged on the lower surface of the diamond substrate in order from top to bottom; wherein, the hydrogen passivation A diamond core detector with a silicon terminal ohmic contact electrode is prepared by the method described in any one of claims 1 to 8.

Beneficial effects of the present invention:

1. The present invention forms a silicon-terminated doped diamond layer with C-Si bonds and forms a hydrogen-passivated silicon-terminated diamond surface with C-Si-H bonds on the silicon-terminated doped diamond layer, which can prevent surface defects caused by traditional technologies. The problem of excessive contact resistance caused by the oxidation of silicon terminals to form Si-O bonds. At the same time, due to the passivation effect of hydrogen atoms after bonding with silicon, it not only avoids the problem of excessive defect density caused by the silicon dioxide layer formed after silicon is oxidized, but also eliminates a large number of silicon dangling bonds, greatly reducing interface trap effect.

2. By preparing a hydrogen-passivated silicon terminal diamond layer on high-purity intrinsic diamond and preparing an ohmic contact electrode with good performance on top, the present invention can effectively suppress the problem of device performance degradation caused by material defects and electrode contact. Compared with ohmic contact electrodes on hydrogen-terminated diamond, it has the excellent characteristics of strong electrode adhesion, low ohmic contact resistance, and fewer dangling bonds, which can effectively improve device electrode reliability, reduce on-resistance and interface traps effect.

3. Effectively reduce process costs. The invention uses magnetron sputtered silicon thin film as the silicon source, and simultaneously realizes the preparation of silicon terminals and the formation of hydrogen-passivated silicon terminals through hydrogen plasma treatment. The preparation process is simple, the cost is low, and it can meet the needs of large-scale preparation.

Description of drawings

Figure 1 is a schematic structural diagram of a diamond core detector with a hydrogen-passivated silicon terminal ohmic contact electrode provided by an embodiment of the present invention;

Figure 2 is a flow chart of a method for preparing a diamond core detector with a hydrogen-passivated silicon terminal ohmic contact electrode provided by an embodiment of the present invention;

Figure 3 is a schematic process diagram of a method for preparing a diamond core detector with a hydrogen-passivated silicon terminal ohmic contact electrode provided by an embodiment of the present invention;

Figure 4 is an XPS result diagram of the Si 2p spectrum of a hydrogen-passivated silicon-terminated diamond provided by an embodiment of the present invention;

Figure 5 is an XPS result diagram of the C1s spectrum of a hydrogen-passivated silicon-terminated diamond provided by an embodiment of the present invention;

Figure 6 is a hydrogen passivated silicon terminal diamond SMIS test result diagram provided by an embodiment of the present invention;

Figure 7 is a diagram showing the ohmic contact results between a hydrogen-passivated silicon-terminated diamond and Au provided by an embodiment of the present invention.

Reference signs

1-Diamond substrate; 2-First silicon terminal doped diamond layer; 3-First hydrogen passivated silicon terminal diamond layer; 4-Second silicon terminal doped diamond layer; 5-Second hydrogen passivated silicon terminal diamond layer layer; 6-first electrode; 7-second electrode.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1

In order to solve the above problems, embodiments of the present invention provide a method for preparing a diamond core detector with a hydrogen-passivated silicon terminal ohmic contact electrode, as shown in Figure 2, including:

S1, select high-purity intrinsic diamond according to the preset impurity content requirements and preset dislocation density requirements, and clean them to obtain diamond substrate 1;

S2, forming the first silicon film on the upper surface of the diamond substrate 1;

S3, perform preset process treatment on the first silicon film, including: using hydrogen plasma to provide a high-temperature environment in MPCVD, so that silicon atoms in contact with the upper surface of the diamond substrate 1 are thermally diffused into the diamond lattice, forming a C -The first silicon terminal of the Si bond is doped with the diamond layer 2; then the hydrogen plasma pressure and power are increased to etch and remove the residual silicon film that has not diffused into the diamond on the surface, and finally the upper surface of the first silicon terminal is doped with the diamond layer 2 Forming a first hydrogen-passivated silicon-terminated diamond layer 3 having C-Si-H bonds;

S4, form a second silicon film on the lower surface of the diamond substrate 1 after completing the preset process;

S5, perform a preset process on the second silicon film to form a second silicon terminal doped diamond layer 4 and a second hydrogen passivated silicon terminal diamond layer 5;

S6, prepare the first electrode 6 on the surface of the first hydrogen-passivated silicon-terminated diamond layer 3, and prepare the second electrode 7 on the surface of the second hydrogen-passivated silicon-terminated diamond layer 5, to obtain a diamond core detector.

In the embodiment of the present invention, hydrogen plasma treatment is used in MPCVD. While preparing silicon terminal diamond, the surface silicon terminal is also hydrogen passivated, making it difficult to be oxidized in the air. Since hydrogen atoms fill the surface dangling bonds of the silicon terminal, Thereby exhibiting good ohmic contact performance.

Each step is explained separately below.

For S1, high-purity intrinsic diamond is selected according to the preset impurity content requirements and preset dislocation density requirements, and is cleaned to obtain diamond substrate 1.

Specifically, the preset impurity content requirement is that the impurity concentration of nitrogen and boron is less than 5 ppb; the preset dislocation density requirement is that the dislocation density is less than 10 ³ cm ^-2 .

Choosing high-purity intrinsic diamond with high quality, low impurity content and low dislocation density as the substrate can effectively improve the performance of nuclear detectors. Higher impurity content will form more scattering centers, recombination centers and traps inside the intrinsic diamond layer, thereby affecting the transport of radiated carriers inside the device and reducing the device's response to irradiation. Dislocations in the body can also cause non-ideal phenomena such as leakage in the device, affecting the overall performance of the device. In addition, high-purity intrinsic diamond with high quality, low impurity content and low dislocation density also provides reliable guarantee for the control of doping concentration distribution and electrode performance under the prepared ohmic contact electrode.

Specifically, the selected high-purity intrinsic diamond is cleaned, including:

The selected high-purity intrinsic diamond was ultrasonically cleaned sequentially for 15 minutes in a strong acid mixed solution of H ₂ SO ₄ :HNO ₃ , acetone, ethanol, and deionized water at 200°C.

The obtained substrate was ultrasonically cleaned in a strong acid mixed solution (H ₂ SO ₄ : HNO ₃ ), acetone, ethanol, and deionized water at 200°C for 15 minutes to remove contaminants and organic residues on the substrate surface to obtain the surface The clean diamond sheet, that is, the diamond substrate 1, is shown in (a) of Figure 3.

For S2, a first silicon film is formed on the upper surface of the diamond substrate 1.

This step specifically includes:

On the upper surface of the diamond substrate 1, an intrinsic silicon target with a purity of 99.9999% is used to deposit a silicon film with a thickness of 250nm to 350nm through magnetron sputtering as the first silicon film, as shown in Figure 3(b) It is shown in the dotted shaded area above 1 in the figure.

The 99.9999% high-purity intrinsic silicon target used in this step provides a reliable guarantee for the quality of subsequent silicon terminal doping, reducing the contamination of diamond by other impurities during the etching process. The specific thickness of the silicon film is determined by ellipsometry. The instrument determines that it is between 250nm and 350nm. A thicker silicon film can effectively reduce the etching effect of hydrogen plasma on silicon terminal doped diamond and ensure the concentration of surface silicon terminal doping.

For S3, the first silicon film is subjected to a preset process, including: using hydrogen plasma to provide a high-temperature environment in MPCVD, so that the silicon atoms in contact with the upper surface of the diamond substrate 1 are thermally diffused into the diamond lattice, forming a The first silicon terminal of the C-Si bond is doped with the diamond layer 2; then the hydrogen plasma pressure and power are increased to etch and remove the residual silicon film that has not diffused into the diamond on the surface, and finally the first silicon terminal is doped with the diamond layer 2 A first hydrogen-passivated silicon-terminated diamond layer 3 having C-Si-H bonds is formed on the surface.

Specific S3 includes:

Place the diamond substrate with the first silicon film deposited on the surface into MPCVD, and under the conditions of 500-600 sccm hydrogen flow, 50-100 mbar pressure, and 2000-2500 W microwave power, heat it up to 600-800°C to perform hydrogen plasma etching. High-temperature treatment for 5 to 10 minutes allows silicon atoms to thermally diffuse into the diamond lattice to generate C-Si bonds, forming the first silicon terminal doped diamond layer 2;

Under the conditions of 600-700sccm hydrogen flow, 150-200mbar pressure, and 3500-4000W microwave power, raise the temperature to 800-1000°C and perform hydrogen plasma etching for 5-10 minutes; use hydrogen plasma to etch the remaining first silicon film. After the first silicon film is completely removed, the action of hydrogen plasma under high temperature and high pressure is used to generate C-Si-H bonds on the upper surface of the first silicon terminal doped diamond layer 2 to form a first hydrogen passivated silicon terminal diamond. Layer 3.

Through the above steps, the hydrogen-passivated silicon-terminated diamond structure is prepared on one side of the diamond substrate, as shown in (c) of Figure 2. The thickness of the first silicon terminal doped diamond layer 2 is 1 to 2 μm. A heavily doped silicon terminal diamond layer with a concentration of 1×10 ²⁰ cm ³ is realized at 1 to 5 nm on the upper surface of the diamond substrate 1, and a first hydrogen passivation layer is formed on the surface due to hydrogen plasma etching and hydrogen adsorption. Silicone terminal diamond layer 3. The hydrogen-passivated silicon terminal diamond layer is mainly composed of C-Si bonds and C-Si-H bonds.

In the embodiment of the present invention, lower pressure and power are first used to perform hydrogen plasma treatment on the diamond substrate on which the silicon film has been deposited, which ensures diffusion uniformity and reduces the etching effect of the hydrogen plasma on the surface silicon film. Subsequently, increasing the pressure and power in the MPCVD system helps to increase the etching rate of the surface silicon film by hydrogen plasma and the formation of hydrogen passivation.

At present, the preparation of silicon terminals on diamond surfaces mainly uses the selective growth method with SiO ₂ as a mask and the molecular beam deposition method with high-temperature annealing in a vacuum environment to form C-Si bonds. These two methods cannot characterize and analyze the number and uniformity of silicon-terminated diamond C-Si bonds during the device preparation process. They can only test the electrical properties after the overall preparation is completed, and cannot guarantee the high performance and yield of the prepared device. resulting in loss of process costs. In addition, the dangling bonds of silicon on the surface of silicon-terminated diamond based on the above two processes are easily oxidized, and Si will combine with O to form a C-Si-O/ _SiO2 structure. Due to the high electronegativity of oxygen, its surface electron affinity The sum energy is significantly increased, so that the oxidized silicon-terminated diamond exhibits high-resistance properties and cannot achieve low-resistance ohmic contact.

In S2 and S3 of the embodiment of the present invention, the silicon source is provided by depositing a silicon film on the diamond surface, which can be realized by ordinary MPCVD equipment and has good process compatibility. And due to hydrogen plasma treatment and etching in the MPCVD system, hydrogen atoms passivate the remaining dangling bonds in the Si atoms on the diamond surface that are not involved in forming C-Si bonds, forming a C-Si-H bond structure on the surface. It effectively prevents isolated silicon bonds from combining with oxygen in the environment and improves the interface quality.

Figures 4 and 5 are XPS results of the Si 2p spectrum of hydrogen-passivated silicon-terminated diamond and XPS results of the C1s spectrum of hydrogen-passivated silicon-terminated diamond. The Si 2p spectrum is the photoelectron energy measured when the 2p orbital electrons in silicon atoms are excited, and can be used to observe the bonding between silicon and other elements. The C1s spectrum is the photoelectron energy measured when the 1s orbital electrons in carbon atoms are excited, and carbon can be observed. Bonding with other elements. It can be seen from Figures 4 and 5 that a C-Si-H bond structure dominated by C-Si and Si-H is formed on the hydrogen-passivated silicon-terminated diamond surface, which greatly suppresses C-H, C-O and Si-O bonds. The generation of type.

Figure 6 shows the SMIS test results of hydrogen-passivated silicon-terminated diamond. The test results show that hydrogen-passivated silicon-terminated diamond achieves a heavily silicon-doped silicon termination with a surface of approximately 1×10 ²⁰ cm ³ , and in the depth range of 0 to 400 nm, the Si doping concentration in the diamond sample is higher than 1 ×10 ¹⁸ cm ³ .

For S4, a second silicon film is formed on the lower surface of the diamond substrate 1 after completing the preset process;

For S5, a preset process is performed on the second silicon film to form a second silicon terminal doped diamond layer 4 and a second hydrogen passivated silicon terminal diamond layer 5.

The same process as S2 and S3 is used for the lower surface of the diamond substrate 1 after S3 treatment. Specifically, the second silicon film is subjected to a preset process, including: using hydrogen plasma to provide a high-temperature environment in MPCVD, so that the silicon atoms in contact with the lower surface of the diamond substrate 1 are thermally diffused into the diamond lattice, forming a The second silicon terminal of the C-Si bond is doped with the diamond layer 4; then the hydrogen plasma pressure and power are increased to etch and remove the residual silicon film that has not diffused into the diamond on the surface, and finally the second silicon terminal is doped with the diamond layer 4 A second hydrogen-passivated silicon-terminated diamond layer 5 having C-Si-H bonds is formed on the surface. The preparation of a hydrogen-passivated silicon-terminated diamond structure was achieved on the other side of the diamond substrate, as shown in (d) of Figure 3.

For S6, the first electrode 6 is prepared on the surface of the first hydrogen-passivated silicon-terminated diamond layer 3, and the second electrode 7 is prepared on the surface of the second hydrogen-passivated silicon-terminated diamond layer 5 to obtain a diamond core detector.

Specifically, the first electrode 6 is prepared on the surface of the first hydrogen-passivated silicon terminal diamond layer 3, and the second electrode 7 is prepared on the surface of the second hydrogen-passivated silicon terminal diamond layer 5, including:

When the material of the electrode is Au, use an electron beam evaporation process to deposit an Au metal layer of 80 to 120 nm in a specified area on the surface of the first hydrogen-passivated silicon terminal diamond layer 3 to form a metal electrode as the first electrode 6;

In a prescribed area on the surface of the second hydrogen-passivated silicon terminal diamond layer 5, an Au metal layer of 80 to 120 nm is deposited using an electron beam evaporation process to form a metal electrode as the second electrode 7, as shown in (e) of Figure 2 Show.

Optionally, the definition of the electrode metal deposition area on the surface of the hydrogen-passivated silicon terminal diamond layer can be performed using a metal mask or photolithography. The metal mask can be directly covered on the surface of the hydrogen-passivated silicon terminal diamond layer to deposit the electrode metal. Photolithography is done by applying glue, exposing, and developing on the surface of the hydrogen-passivated silicon terminal diamond layer to form the specified exposure. area, where electrode metal is then deposited.

Figure 7 is the ohmic contact diagram of Au and hydrogen-passivated silicon-terminated diamond. The contact resistance between Au and hydrogen-passivated silicon-terminated diamond is 2.43Ω·mm, and the contact resistivity is 1.02×10 ^-5 Ω·cm ² , which is lower than the ohmic contact electrode on hydrogen-terminated diamond, indicating that hydrogen-passivated silicon-terminated diamond has Good ohmic contact resistance and contact resistivity.

Example 2

The embodiment of the present invention adopts the same steps S1 to S5 as those in Embodiment 1.

In S6, when the electrode materials are Ti and Au:

Specifically, the first electrode 6 is prepared on the surface of the first hydrogen-passivated silicon terminal diamond layer 3, and the second electrode 7 is prepared on the surface of the second hydrogen-passivated silicon terminal diamond layer 5, including:

When the electrode materials are Ti and Au, a Ti metal layer of 20 to 30 nm and an Au metal of 90 to 100 nm are sequentially deposited using an electron beam evaporation process in a prescribed area on the surface of the first hydrogen-passivated silicon terminal diamond layer 3 The layer is annealed in a rapid thermal annealing RTP device to form an ohmic contact electrode as the first electrode 6;

In a prescribed area on the surface of the second hydrogen-passivated silicon terminal diamond layer 5, a 20-30nm Ti metal layer and a 90-100nm Au metal layer are sequentially deposited using an electron beam evaporation process, and annealed in a rapid thermal annealing RTP equipment. Process to form an ohmic contact electrode as the second electrode 7; wherein, the time of the annealing process is 25 to 30 seconds, and the temperature of the annealing process is 600 to 650°C.

Other steps and parameters are the same as in Example 1.

In the diamond nuclear detector with hydrogen-passivated silicon terminal ohmic contact electrode obtained in this embodiment, the materials of the first electrode 6 and the second electrode 7 are Ti and Au, the thickness of the Ti metal layer is 20-30 nm and the Au metal The thickness of the layer is 90-100nm.

Example 3

The embodiment of the present invention adopts the same steps S1 to S5 as those in Embodiment 1.

In S6, when the electrode materials are Ti, Pt and Au:

Specifically, the first electrode 6 is prepared on the surface of the first hydrogen-passivated silicon terminal diamond layer 3, and the second electrode 7 is prepared on the surface of the second hydrogen-passivated silicon terminal diamond layer 5, including:

When the electrode materials are Ti, Pt and Au, a 40-60nm Ti metal layer, 80-100nm Ti metal layer and 80-100nm Ti metal layer are sequentially deposited using an electron beam evaporation process in a prescribed area on the surface of the first hydrogen-passivated silicon terminal diamond layer 3. The Pt metal layer and the Au metal layer of 40 to 60 nm are thermally annealed in a nitrogen atmosphere to form an ohmic contact electrode as the first electrode 6 .

In a prescribed area on the surface of the second hydrogen-passivated silicon terminal diamond layer 5, a 40-60nm Ti metal layer, an 80-100nm Pt metal layer and a 40-60nm Au metal layer are sequentially deposited using an electron beam evaporation process. Rapid thermal annealing is performed in a nitrogen atmosphere to form an ohmic contact electrode as the second electrode 7; the rapid thermal annealing temperature is 750-850°C, and the rapid thermal annealing time is 20-30 seconds.

Other steps and parameters are the same as in Example 1.

In the diamond nuclear detector with hydrogen-passivated silicon terminal ohmic contact electrode obtained in this embodiment, the materials of the first electrode 6 and the second electrode 7 are Ti, Pt and Au, and the thickness of the Ti metal layer is 40-60 nm. The thickness of the Pt metal layer is 80 to 100 nm, and the thickness of the Au metal layer is 40 to 60 nm.

Example 4

Through S1 to S6 in Example 1, Example 2 or Example 3, a diamond core detector with a hydrogen-passivated silicon terminal ohmic contact electrode can be produced.

Specifically, a diamond core detector with a hydrogen-passivated silicon terminal ohmic contact electrode, as shown in Figure 1, includes:

Diamond substrate 1, first silicon terminal doped diamond layer 2, first hydrogen passivated silicon terminal diamond layer 3, second silicon terminal doped diamond layer 4, second hydrogen passivated silicon terminal diamond layer 5, first electrode 6 and the second electrode 7; where,

The upper surface of the diamond substrate 1 is provided with a first silicon terminal doped diamond layer 2, a first hydrogen passivated silicon terminal diamond layer 3 and a first electrode 6 in order from bottom to top;

The lower surface of the diamond substrate 1 is provided with a second silicon terminal doped diamond layer 4, a second hydrogen passivated silicon terminal diamond layer 5 and a second electrode 7 in order from top to bottom; wherein, the hydrogen passivated silicon terminal ohmic contact electrode The diamond core detector is prepared by the method of any one of claims 1 to 8.

In the embodiment of the present invention, magnetron sputtering silicon thin film is used as the silicon source, and hydrogen plasma treatment is used in MPCVD. While preparing the silicon terminal diamond, the silicon terminal on the surface is also hydrogen passivated, and the silicon terminal is passivated based on hydrogen. A high-performance ohmic contact diamond nuclear detector was prepared from diamond. Compared with the method of preparing silicon terminals through diamond selective growth and molecular beam deposition, the embodiment of the present invention uses a silicon film sputtered on diamond as a silicon source, and simultaneously achieves the preparation and production of silicon terminals on diamond through hydrogen plasma treatment. The formation of hydrogen-passivated silicon terminals can prevent the problem of excessive contact resistance caused by the oxidation of surface silicon terminals to form Si-O bonds in traditional technology. At the same time, due to the passivation effect of hydrogen atoms after bonding with silicon, it not only avoids the problem of excessive defect density caused by the silicon dioxide layer formed after silicon is oxidized, but also eliminates a large number of silicon dangling bonds, greatly reducing By eliminating the interface trap effect, a hydrogen-passivated silicon-terminated diamond layer can be prepared on high-purity intrinsic diamond and an ohmic contact electrode with good performance can be prepared on top, thereby improving the performance of the diamond core detector. In addition, the present invention uses magnetron sputtered solid silicon as the silicon source, and simultaneously realizes the preparation of silicon terminals and the formation of hydrogen-passivated silicon terminals through traditional MPCVD equipment. The preparation process is simple and low-cost, and can meet the needs of large-scale preparation.

It should be noted that in the description of the present invention, it needs to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "Front", "Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inside", "Outside", "Clockwise", "Counterclockwise" The indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. They are not intended to indicate or imply that the device or element referred to must have a specific orientation or in a specific manner. orientation construction and operation and therefore should not be construed as limitations of the invention.

In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more than two, unless otherwise explicitly and specifically limited.

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "an example," "specific examples," or "some examples" or the like means that specific features are described in connection with the embodiment or example. , structures, materials or features are included in at least one embodiment or example of the invention. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may join and combine the different embodiments or examples described in this specification.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (9)

1. A method for preparing a diamond nuclear detector of a hydrogen passivated silicon terminal ohmic contact electrode, which is characterized by comprising the following steps:

selecting high-purity intrinsic diamond according to the preset impurity content requirement and the preset dislocation density requirement, and cleaning to obtain a diamond substrate (1);

forming a first silicon film on the upper surface of the diamond substrate (1);

and carrying out preset process treatment on the first silicon film, wherein the preset process treatment comprises the following steps: providing a high temperature environment in MPCVD by utilizing hydrogen plasma, and thermally diffusing silicon atoms in contact with the upper surface of the diamond substrate (1) into a diamond lattice to form a first silicon terminal doped diamond layer (2) with C-Si bonds; then, raising the pressure and power of hydrogen plasma to etch and remove the residual silicon film which is not diffused into the diamond on the surface, and finally forming a first hydrogen passivation silicon terminal diamond layer (3) with C-Si-H bonds on the upper surface of the first silicon terminal doped diamond layer (2);

forming a second silicon film on the lower surface of the diamond substrate (1) after the preset process treatment is completed;

carrying out the preset process treatment on the second silicon film to form a second silicon terminal doped diamond layer (4) and a second hydrogen passivated silicon terminal diamond layer (5);

and preparing a first electrode (6) on the surface of the first hydrogen-passivated silicon terminal diamond layer (3), and preparing a second electrode (7) on the surface of the second hydrogen-passivated silicon terminal diamond layer (5) to obtain the diamond core detector.

2. The method for preparing a diamond nuclear detector of a hydrogen passivated silicon termination ohmic contact electrode according to claim 1, characterized in that the preset impurity content requirement is that the impurity concentration of nitrogen and boron is less than 5ppb; the preset dislocation density is less than 10 ³ cm ^-2 。

3. The method of fabricating a diamond nuclear detector for hydrogen passivated silicon termination ohmic contact electrodes of claim 2, wherein cleaning the selected high purity intrinsic diamond comprises:

mixing the selected high-purity intrinsic diamond with strong acid mixed solution H at 200 DEG C ₂ SO ₄ :HNO ₃ Sequentially performing ultrasonic cleaning on the mixture for 15min in acetone, ethanol and deionized water.

4. The method of manufacturing a diamond nuclear detector of hydrogen passivated silicon termination ohmic contact electrode according to claim 1, characterized by forming a first silicon film on the upper surface of the diamond substrate (1), comprising:

and depositing a silicon film with the thickness of 250-350 nm on the upper surface of the diamond substrate (1) by magnetron sputtering by adopting an intrinsic silicon target with the purity of 99.9999 percent as a first silicon film.

5. The method for preparing a diamond nuclear detector for hydrogen passivated silicon termination ohmic contact electrode of claim 4 wherein said first silicon film is subjected to a predetermined process comprising: providing a high temperature environment in MPCVD by utilizing hydrogen plasma, and thermally diffusing silicon atoms in contact with the upper surface of the diamond substrate (1) into a diamond lattice to form a first silicon terminal doped diamond layer (2) with C-Si bonds; and then raising the pressure and power of hydrogen plasma to etch and remove the residual silicon film which is not diffused into the diamond on the surface, and finally forming a first hydrogen passivation silicon terminal diamond layer (3) with C-Si-H bonds on the upper surface of the first silicon terminal doped diamond layer (2), wherein the method comprises the following steps:

placing the diamond substrate with the first silicon film deposited on the surface into MPCVD, heating to 600-800 ℃ under the conditions of 500-600 sccm hydrogen flow, 50-100 mbar pressure and 2000-2500W microwave power, and carrying out hydrogen plasma etching high-temperature treatment for 5-10 min to enable silicon atoms to thermally diffuse into diamond crystal lattice to generate C-Si bonds, so as to form the first silicon terminal doped diamond layer (2);

heating to 800-1000 ℃ under the conditions of 600-700 sccm hydrogen flow, 150-200 mbar pressure and 3500-4000W microwave power, and carrying out hydrogen plasma etching for 5-10 min; and etching the residual first silicon film by utilizing hydrogen plasma, and generating C-Si-H bonds on the upper surface of the first silicon terminal doped diamond layer (2) by utilizing the action of the hydrogen plasma at high temperature and high pressure after the first silicon film is completely removed to form the first hydrogen passivated silicon terminal diamond layer (3).

6. The method of manufacturing a diamond core detector for hydrogen passivated silicon terminated ohmic contact electrode according to claim 1, characterized in that a first electrode (6) is manufactured on the surface of the first hydrogen passivated silicon terminated diamond layer (3) and a second electrode (7) is manufactured on the surface of the second hydrogen passivated silicon terminated diamond layer (5), comprising:

when the electrode is made of Au, depositing an Au metal layer of 80-120 nm on a preset area on the surface of the first hydrogen passivation silicon terminal diamond layer (3) by utilizing an electron beam evaporation process to form a metal electrode as a first electrode (6);

and depositing an Au metal layer of 80-120 nm on a preset area on the surface of the second hydrogen passivation silicon terminal diamond layer (5) by utilizing an electron beam evaporation process to form a metal electrode as a second electrode (7).

7. The method of manufacturing a diamond core detector for hydrogen passivated silicon terminated ohmic contact electrode according to claim 1, characterized in that a first electrode (6) is manufactured on the surface of the first hydrogen passivated silicon terminated diamond layer (3) and a second electrode (7) is manufactured on the surface of the second hydrogen passivated silicon terminated diamond layer (5), comprising:

when the materials of the electrodes are Ti and Au, sequentially depositing a Ti metal layer with the thickness of 20-30 nm and an Au metal layer with the thickness of 90-100 nm on a preset area on the surface of the first hydrogen passivation silicon terminal diamond layer (3) by using an electron beam evaporation process, and performing annealing treatment in rapid thermal annealing RTP equipment to form an ohmic contact electrode as a first electrode (6);

sequentially depositing a Ti metal layer with the thickness of 20-30 nm and an Au metal layer with the thickness of 90-100 nm on a preset area on the surface of the second hydrogen passivated silicon terminal diamond layer (5) by using an electron beam evaporation process, and performing annealing treatment in rapid thermal annealing RTP equipment to form an ohmic contact electrode as a second electrode (7);

wherein the time of the annealing treatment is 25-30 seconds, and the temperature of the annealing treatment is 600-650 ℃.

8. The method of manufacturing a diamond core detector for hydrogen passivated silicon terminated ohmic contact electrode according to claim 1, characterized in that a first electrode (6) is manufactured on the surface of the first hydrogen passivated silicon terminated diamond layer (3) and a second electrode (7) is manufactured on the surface of the second hydrogen passivated silicon terminated diamond layer (5), comprising:

when the materials of the electrodes are Ti, pt and Au, sequentially depositing a Ti metal layer of 40-60 nm, a Pt metal layer of 80-100 nm and an Au metal layer of 40-60 nm on a preset area on the surface of the first hydrogen passivation silicon terminal diamond layer (3) by using an electron beam evaporation process, and performing rapid thermal annealing in a nitrogen atmosphere to form an ohmic contact electrode as a first electrode (6);

sequentially depositing a Ti metal layer of 40-60 nm, a Pt metal layer of 80-100 nm and an Au metal layer of 40-60 nm on a preset area on the surface of the second hydrogen passivated silicon terminal diamond layer (5) by using an electron beam evaporation process, and performing rapid thermal annealing in a nitrogen atmosphere to form an ohmic contact electrode as a second electrode (7);

wherein the temperature of the rapid thermal annealing is 750-850 ℃, and the time of the rapid thermal annealing is 20-30 seconds.

9. A diamond nuclear detector for hydrogen passivating a silicon termination ohmic contact electrode, comprising:

the diamond substrate (1), a first silicon terminal doped diamond layer (2), a first hydrogen passivated silicon terminal diamond layer (3), a second silicon terminal doped diamond layer (4), a second hydrogen passivated silicon terminal diamond layer (5), a first electrode (6) and a second electrode (7); wherein,

the upper surface of the diamond substrate (1) is sequentially provided with the first silicon terminal doped diamond layer (2), the first hydrogen passivated silicon terminal diamond layer (3) and the first electrode (6) from bottom to top;

the lower surface of the diamond substrate (1) is sequentially provided with the second silicon terminal doped diamond layer (4), the second hydrogen passivated silicon terminal diamond layer (5) and the second electrode (7) from top to bottom; wherein the diamond core detector of the hydrogen passivated silicon termination ohmic contact electrode is formed by the method of any one of claims 1-8.